中文摘要：

采用热分析、光学显微镜、拉伸测试与广角X-射线衍射等方法研究了双轴拉伸聚丙烯薄膜用均聚聚丙烯（h-BOPP）与含有少量乙烯单体的共聚聚丙烯（c-BOPP）材料的熔融、结晶特性和拉伸性能．研究发现，与均聚样品相比，共聚样品的等规度低，结晶速率慢，在相同的结晶温度条件下，其半结晶时间较长．退火处理后，结晶完善程度增加，均聚和共聚样品的断裂伸长率均比其未退火处理的低．但共聚样品的结晶速率慢，经过退火处理后其结晶完善性稍低于均聚样品，所以其断裂伸长率略大于均聚样品．经过拉伸形变后，样品的结晶结构被部分破坏，取向的非晶的分子链在后续的升温过程中很容易重构为更加完善的结晶结构，由于分子链结构的差异，均聚样品的结晶重构能力更强．阐释了由于链结构的不同导致的BOPP拉伸性能和结晶性能差异的机理．

英文摘要：

The melting behavior, crystallizing characteristics and tensile properties of biaxially oriented polypropylene （PP homopolymer for BOPP film （h-BOPP） and PP-PE copolymer for BOPP film （c-BOPP）） were investigated by differential scanning calorimetry （DSC） ,optical microscopy （OM） , tensile test and wide angle X-ray diffraction （WAXD）. The results showed that compared with h-BOPP, the isotacticity and crystallization rate of c-BOPP were lower, and its half crystallization time was longer at the same crystallization temperature. For h-BOPP and c-BOPP samples without annealing,the elongation at break was higher. However, after annealing at 140 ~C for 2 h,the elongation at break of both h-BOPP and e-BOPP decreased a lot, as the more perfect crystallites formed. It was believed that crystals of higher perfection had less ability to rearrange themselves under stretching and therefore could not sustain large extensional deformation. Since there are many ethylene segments in the molecular chains that could inhibit the nucleation and crystallization, the crystallization rate of c-BOPP was low, resulting in lower perfect crystallites after annealing. So the elongation at break of c-BOPP was a little more than that of h-BOPP. In addition, the crystalline structure was proven to be partially destroyed under the extensional deformation, and the oriented noncrystalline molecular chains could be easily reorganized into more perfect crystals in the post heating runs. Due to the ethylene segments in the molecular chains of h-BOPP, the oriented noncrystalline molecular chains of h-BOPP could be easier reorganized. This paper explained the mechanism related to the differences between the tensile properties and crystallization behavior of BOPP with different molecular chains.